Prevalence of Helicobacter pylori in children and their family members in a district in Turkey.

The aim of this study was to determine the prevalence of Helicobacter pylori among children and their family members and to evaluate some epidemiologic characteristics. The study included 275 children, aged 1-15 year(s), suffering from different gastrointestinal complaints. Blood serology and stool antigen testing were used for the diagnosis of infection due to H. pylori. Sixty-five (23.6%) of the 275 children were positive for H. pylori, and this positivity had a significantly increasing correlation with age (p<0.001). H. pylori-associated infection was observed among 45 (69.2%) and 17 (8%) mothers in the H. pylori-infected and non-infected groups respectively (p<0.0001). Most children and their families infected with H. pylori were living in an urban area. The findings suggest that infection due to H. pylori is a problem for this district area, and all children having any gastrointestinal complaints should be examined whether H. pylori was prevalent among their family members.


INTRODUCTION
Helicobacter pylori is a spiral gram-negative microorganism that is distributed worldwide. It is estimated that over 50% of the world population are infected with H. pylori (1)(2)(3)(4)(5). H. pylori-associated infection is either usually clinically silent or its signs and symptoms are non-specific. Gastroesophageal reflux, esophagitis, delayed gastric emptying, and various motilitiy disorders can be a sign or symptom of it (1)(2)(3)(4)(5). However, these symptoms are seen in many childhood illnesses. Younger children with peptic complaints may not have symptoms as clear as those of older children, and diagnosis of infection due to H. pylori is more difficult (6)(7)(8)(9)(10).
The epidemiology of H. pylori-associated infection is variable, since the prevalence is significantly higher and infection occurs in earlier ages in developing or poor countries compared to developed countries (11). In Turkey, the seroprevalence of infection due to H. pylori in children has been reported as high as 43.9% and 53.9% (3,6,7). There is an obvious public-health problem of H. pylori-associated infection, and thus, to design targeted, cost-effective prevention strategies, elucidation of the mode of transmission for this infection is crucial. Infection due to H. pylori is typically acquired in early childhood and usually persists throughout life unless specific treatment is given (12).
Definitive routes of its transmission have not yet been characterized, and the principal reservoir appears to be family members. Person-to-person transmission via the faecal-oral and oral-oral routes have been proposed. Numerous studies also indicate that low socioeconomic status, including domestic overcrowding, is a major risk factor for a higher prevalence of infection (13,14).
Currently, little data exist regarding the epidemiology of H. pylori-associated infection in our region. Therefore, this study was conducted to determine the prevalence of H. pylori among children and also to investigate if there is an association between H. pylori positivity and symptoms of children and their family members in a district in Turkey.

MATERIALS AND METHODS
In total, 275 children with different gastrointestinal complaints, admitted to the Department of Pediatrics, Faculty of Medicine, Yüzüncü Yil University, were examined for H. pylori during May 2003-March 2005. Patients who were aged less than one year or aged over 15 years or who had any other chronic diseases or used medicines which affect the gastrointestinal system were excluded. All children and their families were questioned about gastrointestinal symptoms or complaints, e.g. recurrent abdominal pain, nausea, vomiting, gastroesophageal reflux, dyspeptic complaints. Cases who had both positive serology and positive stool antigen test were accepted as positive for infection due to H. pylori.
Both blood sera and stool specimens were studied in all children and their families. Three mL of venous blood were taken from all children and family members, and those sera were stored at -20 ºC in a deepfreeze. After adequate sera were collected, antibody IgG against H. pylori was detected by the ELISA method. For this procedure (General Biological Corp-GBC No: 6 Innovatien First Road Science Based Ind Park Hsinchu, Taiwan), test-kits were used. The values above the cut-off level were accepted as H. pylori-positive and values below the cut-off level as H. pylori-negative. Hp faecal antigen (Premier H. pylori, Meridian Diagnostic Inc.) tests were performed as a diagnostic panel in all cases.
All patients were asked for information on gastrointestinal symptoms and place of residence (urban or rural) if there are other members of the family who had gastrointestinal complaints.
Statistical analysis was made using chi-square test analysis by the SPSS software (version 11.5). A value of p<0.05 was accepted as significant.
Written informed consents were taken from families for further investigation and analysis. The ethics committee of the hospital approved the study.
Gastrointestinal symptoms were similar among both H. pylori-infected and non-infected children. Some diagnoses of non-infected children were as follows: parasitic infection, peptic ulcer, gastritis, and familial mediterranean fever. Table 2  among children with a family member infected with the bacterium than among children without any infected family member. The differences were significant for mothers, fathers, and also siblings (p<0.0001, Table 3).

DISCUSSION
The prevelance of H. pylori varies from country to country and by age-groups. In the United States, H. pylori positivity in children aged less than 10 years is lower than 5%, whereas it is 10% and 60% among individuals who are aged 20 years and above 60 years respectively (8 (35). The higher prevalence of infection due to H. pylori in parents of infected children suggests person-to-person transmission within the family (36,37). In the present study, we observed rates of higher positivity among children of infected parents compared to other children whose parents were not infected. An infected mother may play a key role in the transmission of H. pylori within the family (38). Mouth secretions of mother which may be contaminated with H. pylori may be transmitted to the infant and child (39,40). Transmission may occur also for using common spoons, the licking of pacifiers, or teats of feeding bottles, or even for chewing or tasting children's food (38).
Person-to-person transmission of H. pylori may be an important mode of disease spread, but the rate of transmission is still a controversial issue (33). However, faecal-oral transmission may play an important role in developing countries (38,41). Transmission of the microorganism may be facilitated due to lack of hygiene, for crowding of people, and through more intimate contact. In addition to the environmental factors contributing to transmission, results of a study suggest that host factors may be important in pathogenesis (43). Boren et al. reported the involvement of Lewis blood group antigen in the attachment of H. pylori to gastric mucosa (42). It was also reported that the HLA DQAI gene contributes to the host response against H. pylori (43). In the present study, we demonstrated a very strong association between the infection status of children and of their mothers.
Findings similar to those in our study, reporting an overall higher rate of infection in an urban population (25.8%) than in a rural population (10.2%), have been reported from Nepal and Viet Nam (44,45), although their rates of infections were higher than ours. Also, a study in Mexico reported that the urban people had the high risk for seropositivity (46).
In conclusion, the present study reports a significant increase in the seroprevalence of infection due to H. pylori with increasing age. It also provides strong evidence for a transmission pathway from family members to children. Urban children have a greater risk for infection due to H. pylori.